Not applicable.
An arrangement for removing oil in accordance with the present invention can be employed in all rolls in which there is a stationary support construction around which the roll mantle revolves and in which it is desirable to drain the oil that is gathered in the roll. Such rolls are, for example, variable-crown rolls in paper or board machines, rolls whose mantle can be shifted in the nip plane in relation to the stationary support construction, and extended-nip rolls.
In such rolls, a problem is whipping of the oil and poor drainage of the oil out of the roll interior. Oil is passed into the space between the loading members and the inner face of the roll mantle for purposes of lubrication, and, also, oil may be sprayed onto the inner face of the roll mantle for purposes of cooling. When the roll mantle revolves, said lubrication oil and cooling oil is gathered on the inner face of the roll mantle by the effect of centrifugal force, being carried along with the inner face of the revolving roll mantle. Said lubrication oil and cooling oil ought to be drained away from the inner face of the mantle as soon as possible in order that the oil could not be whipped when it collides against the loading members and against other support members. Excessive oil gathered on the inner face of the roll mantle also increases the amount of energy needed in order to rotate the roll mantle.
In the applicant""s FI Utility Model No. 2920, an arrangement of equipment is described in connection with a variable-crown roll provided with loading shoes in order to prevent foaming of oil. This arrangement of equipment comprises a separate guide that drags against the inner face of the roll mantle and on said guide a face that guides the oil and by whose means the oil present on the inner face of the roll mantle is doctored and guided as an open flow into a collecting trough attached to the stationary roll axle.
In the applicant""s FI Laid-Open Publication No. 98,318, an arrangement is described for draining of oil out of a roll which comprises a non-revolving roll axle, on which the roll mantle has been fitted revolving. Between the roll mantle and the roll axle, hydraulic loading elements have been fitted, which act upon the inner face of the roll mantle in the nip plane, which are supported on the roll axle, and which are loaded with a pressure medium. Said loading elements comprise pistons fitted in cylinder bores that have been formed in the roll axle and glide shoes supported against the inner face of the roll mantle, which glide shoes are provided with pockets separated by lateral ridges and by intermediate ridges and operating as lubrication spaces. Into at least one of the glide shoes in the roll, an oil drain groove has been formed, which groove communicates through a pipe, hose or equivalent with an oil drain duct provided in the roll axle, the oil being arranged to be drained out of the roll through the glide shoe/shoes.
In the EP Patent No. 812,994, a second equipment is described for guiding of an oil flow in connection with a variable-crown roll. The variable-crown roll comprises a stationary central axle, which is connected with hydraulically loaded cylindrical loading members, and a roll mantle revolving on support of bearings around the central axle. On the outer face of each loading member of circular section, two radial oil guide members have been fitted symmetrically. Further, at the outer ends of the oil guide members, guide plates extending tangentially to the outer face of the loading shoe have been fitted. When the roll is in a lower position and when the roll mantle revolves clockwise, the oil present on the inner face of the roll mantle strikes against the loading member from the forward side and is guided along the face of the loading member into the oil guide member, from which the oil falls down onto the end face of the central axle and from it further into a first oil collecting trough placed in connection with the central axle. From the first oil collecting trough, the oil is passed along a first duct to the centre of the central axle, from where the oil is passed out of the roll. When the roll is in an upper position and when the roll mantle revolves counterclockwise, the oil strikes against the loading members from the rear side, in which case the oil is again guided between the loading members into the ducts formed by the tangential guide plates. From here the oil proceeds as stripes of a width equal to the width of said ducts on the inner face of the roll mantle and strikes against spring-loaded doctors placed at the side of the central axle opposite to the loading members. From the faces of the doctors, which are spring-loaded against the inner face of the roll mantle, the oil falls down onto the end face of the central axle and from there further into a second oil collecting trough placed in connection with the central axle. From the second oil collecting trough, the oil is passed along a second duct to the centre of the central axle, from where the oil is passed out of the roll. The faces of the doctors that are placed against the inner face of the roll mantle are inclined. When the roll is in a lower position, the oil strikes against the wedge face of the doctor and presses the doctor against the spring, in which connection the oil can pass along the inner face of the roll mantle under the doctor.
The object of the present invention is to provide an efficient oil removing arrangement in a roll.
By means of the oil collecting equipments connected with the oil removing arrangements in accordance with the present invention, the oil is not collected by doctoring from the inner face of the roll mantle. Thus, in the oil collecting equipments, the curved face which guides the oil and which is placed closest to the inner face of the roll mantle is placed at a distance from the inner face of the roll mantle. In removing of oil taking place by means of doctoring, the friction between the doctor and the inner face of the roll mantle increases the power required to rotate the roll mantle.
When a curved face is used for guiding the oil, a sufficiently long face that guides the oil can be formed between the outer face of the support construction and the inner face of the roll mantle. With a sufficiently long face that guides the oil, the oil flow can calm down, in which case oil cannot return, as a result of vortex formation, back into circulation onto the inner face of the roll mantle. With a curved face, it is also possible to make efficient use of centrifugal force. Centrifugal force presses the oil flow against the curved face, in which connection the oil flow calms down.
By means of the curved faces of the oil collecting equipments employed in the present invention, economies of space are also obtained, in which case the support construction does not have to be machined so extensively in order to provide space. By means of curved faces, the volumes of the oil collecting equipments can be maximized.
In the following, the invention will be described with reference to the figures in the accompanying drawings, the invention being, however, not supposed to be confined to the details of said illustrations alone.
Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.